Passage Indicator: An Interactive Application for Passage Progress Assessment of Adult Spring/Summer Chinook Passage Indicator Application
The Fish Passage Center (FPC) has developed a monitoring method (i.e. passage indicator) that predicts adult salmon passage rates based on regression models using PIT-tags and adult count data. Passage indicator compares current observations of adult passage to model predictions in real time, and provides an objective assessment of passage progress.
The intention of FPC in developing passage indicator is to provide users the convenience of having multiple methods to assess adult passage progress in one interactive environment. As a good investigator considers multiple aspects and evaluates numerous lines of evidence before reaching a conclusion; similarly, a project management team goes through the exercise to consider hydraulic conditions, water summary, weather forecast, and fish passage progress while planning project operations. Thus, we encourage users of passage indicator to consider a diverse analytic perspective while assessing adult passage progress. It is important for fisheries and operation managers to minimize interruptions during adult upstream passage. At the same time, it can be just as important from the perspective of salmon life cycle, to consider the potential harmful effects of a spill reduction that can direct more juvenile migrants through the powerhouse of an in-river project. The following highlight the key points of our methods and precautions that should be taken before drawing conclusions:
- Predicted adult counts by passage indicator incorporates the variations in observed adult counts for the spring/summer Chinook run-at-large.
- Passage indicator predicts adult spring/summer Chinook travel time and the conversion from Ice Harbor to Lower Granite dam, accounting for seasonality, river flow, water temperature, tagging origin, and juvenile transport history.
- In addition to model predictions, passage indicator compares observed fish travel time with historical fish travel time from Lower Monumental to Little Goose dams, and from Ice Harbor to Lower Granite dam.
- Predictions by passage indicator can be unreliable during early migration season due to small sample sizes.
- Users of passage indicator should consider multiple assessments while monitoring adult passage progress. Assessments should all predominantly agree with one another, and users should investigate conflicting evidence before taking any management actions that may be detrimental for other life stages.